This invention relates to irrigation sprinklers particularly of the type including an internally mounted valve unit. More specifically, this invention relates to an improved locking assembly for releasably retaining a valve unit within a sprinkler housing or the like against becoming a water-driven projectile upon attempted valve unit removal, for example, for maintenance purposes, without first relieving water pressure at the upstream side of the valve unit.
Irrigation systems conventionally include a plurality of water sprinklers connected at predetermined positions to a water supply conduit for providing irrigation water to surrounding vegetation, such as grass, crops, and the like. Water under pressure is coupled to the water supply conduit and further to the sprinklers by appropriate manual or automated remote control operation of one or more control valves. In some irrigation system applications, particularly such as irrigation of golf course greens and the like, it may be desirable to connect the water under pressure within the supply conduit to the sprinklers one at a time or for individually timed watering cycles. In such applications, water sprinklers have been proposed to include an individual valve unit integrated into the base of each sprinkler housing for opening and closing the sprinkler housing to water inflow from the supply conduit, wherein the additional valve unit is typically adapted for convenient remote control operation. Exemplary of such water sprinklers including integrated valve units are the impact drive pop-up sprinklers currently marketed by Rain Bird Sprinkler Mfg. Corp. of Glendora, Calif. under the model designations 47 DR and 51 DR.
The integrated valve units incorporated into water sprinklers of the above-referenced type are commonly installed within the base of the sprinkler housing below a sprinkler spray head assembly typically of the so-called "pop-up" type. The valve unit commonly includes a control chamber into or from which water is bled to control the position of a movable valve member between open and closed positions. When the valve member is closed, water flow from the supply conduit into the sprinkler housing is preventing and the pop-up spray head assembly normally retracts to a concealed position within the sprinkler housing. Conversely, when the valve member is open, water under pressure flows into the sprinkler housing to elevate the spray head assembly for discharging water outwardly to irrigate surrounding vegetation. However, valve units of this general type are sometimes clogged by dirt, grit, and the like commonly present in many water supply systems, whereby periodic removal of the valve unit from the sprinkler housing is required for maintenance cleaning purposes.
In the past, to facilitate removal of a valve unit integrated into the base of a water sprinkler, the valve unit has been releasably seated in position by a simple snap ring. When valve unit maintenance is required, the pop-up spray head assembly is removed from above and the snap ring is removed quickly and easily to access the valve unit. However, it is sometimes possible to remove the snap ring without first relieving water pressure within the supply conduit at the upstream side of the valve unit, such as by closure of a main system control valve, whereupon the water pressure can drive the valve unit as a projectile from the water sprinkler creating a risk of injury to the person removing the snap ring. Attempts to alleviate this problem by providing interengageable undercut surfaces on the sprinkler housing and snap ring have not always prevented snap ring removal with the upstream side of the valve unit subjected to significant water pressure.
There exists, therefore, a significant need for an improved locking device for releasably securing a valve unit into the base of a sprinkler housing or the like, wherein the locking device permits facilitated valve unit removal while safeguarding against injury upon attempted valve unit removal prior to relieving water pressure at the upstream side thereof. The present invention fulfills these needs and provides further related advantages.